1. Field of the Invention
The present invention relates to a zipper used for reclosable packages and the method of sealing the zipper to the reclosable package. In particular, the present invention relates to a concave shaped seal base or bridge on a webless zipper profile and a corresponding convex sealing bar to seal the webless zipper to the reclosable package in a form fill seal or similar apparatus.
2. Description of the Prior Art
In the prior art, the design and manufacture of reclosable packages, particularly by form fill seal methods, is well developed. However, further improvements leading to both decreased set-up and maintenance and higher manufacturing throughput are always desired.
In particular, flat seal bars are used for the sealing of webless zippers in form fill seal apparatus. However, this requires a proper set-up procedure in order to avoid manufacturing problems relating to the seal between the base or bridge and the package wall. Such problems include deficiencies in the tracking of the zipper relative to the seal bars, deficiencies in the uniformity of the seal and sensitivity to misaligned sealing equipment.
Any wandering or misalignment of the profile may create a seal which is biased to one side.